We are never happy with what we have. The commercial rat race is fed by an endless cycle of new technology, innovation, renewal, production, sales, income, food on the table, wealth,... I guess it's up to the individual and what it decides on, but generally we tend to be subject to the larger scheeme of things. At the top of the chain some accumulate wealth and riches, while others are forced to spend the little they have.
In a 5 to 10 year period new and improved features will be available, you might even have a phone app reminding you of settings and sorting out details on your latest projects. I know some will go for it, even if it turns out to be a short lived fad.
Somethings have to push things forward, and we are all pressured to be subjects to it. We would not have new sewing machines made if not. On the other hand, production adjusts to people's needs and what they ask for. We could always ask for better quality. It's just that some of us still like an old cast iron straight stitcher ;- ) If the demand is large enough there will be after marked replacements, or we are left to deal with it on our own. It costs too keep up service and production of things, there has to be a profit on everything to be worth it. I don't think anyone would bother repairing and keeping up flimsily made models. Some brands keep up availablility of accessories longer than others, I can still by new Bernina feet for a 730 record, but I guess not all can be found new. Hunting down used and vintage isn't too bad either.
On fleabay
anything can turn up.